


Kill For You

by vampireisthenewblack



Category: Teen Wolf (TV)
Genre: Bladed Weapons, Canon-Typical Violence, Established Relationship, Gen, Kanima Venom, Mountain Ash, Non-Linear Narrative, Post-3b AU, Wolfsbane, firearms
Language: English
Status: Completed
Published: 2014-05-05
Updated: 2014-05-05
Packaged: 2018-01-22 01:03:35
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence
Chapters: 1
Words: 2,053
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1570232
Author URL: https://archiveofourown.org/users/vampireisthenewblack/pseuds/vampireisthenewblack
Summary: <blockquote class="userstuff">
              <p>Kate Takes Derek. Stiles snaps.</p>
<p>Or, the one where Stiles embraces his inner sociopath, and Kate doesn't stand a chance.</p>
            </blockquote>





	Kill For You

**Author's Note:**

  * In response to a prompt by Anonymous in the [killkate3b](https://archiveofourown.org/collections/killkate3b) collection. 



> **Prompt:**
>
>> Kate takes Derek. Stiles snaps.
>> 
>> Or, the one where Stiles embraces his inner sociopath, and Kate doesn't stand a chance.
> 
> A requirement of fills for this prompt meme is that Kate must die. If you have a problem with that, I suggest you go [elsewhere](http://www.archiveofourown.org).
> 
> 'Author Chose Not to Use Archive Warnings' means that any of the AO3 warnings may be present in this work. Any wank will be reported.

Stiles works his way through Deaton's office methodically, pocketing vials and jars with only cursory examination. He knows what he needs, what he's looking for, where it's kept.

* * *

_"He's gone," Scott says._

_Stiles shakes his head. "She's got him locked up somewhere, I know it. We've just got to find out where, then we can get him back."_

_"I know how you feel, Stiles. I just—" Scott drags his teeth over his lower lip, digs his fingernails into his palms. "I don't want anyone else to die."_

_"Right," Stiles mutters as he walks away. "Derek's an acceptable loss."_

* * *

There's just enough moonlight to see by as Stiles makes his way down an alley on the edge of town. He holds his bag close to his body, watches his feet carefully. His destination is upwind, and he hopes his scent is further masked by the stink of old blood from the abattoir that dominates the industrial area.

There's a warehouse that's stood empty for a decade down here, but just a few days ago it started drawing vast amounts of power from the grid.

Stiles had to impersonate a police officer to get that information, and he doesn't care. He doesn't even feel guilty that his father could lose his job if anyone found out.

All he cares about now is getting Derek back.

* * *

_"He's your nephew," Stiles spits, as he shoves Peter back against the wall. "Your family. You're just going to write him off?"_

_Peter smirks, but refrains from pushing Stiles back. "Derek's dead, Stiles. Or he may as well be. Anyone who goes looking for him will suffer the same fate, and I'm sorry. I prefer life."_

* * *

Stiles waits for an 18-wheeler to rumble by on the main road, then cracks open a side door with a crowbar. He holds it like a weapon as he slips through, careful to be as silent as possible as he pushes the door back into its frame.

A slip, a stumble, is all it will take to alert Kate to his presence. He can't risk it.

All he can see are shapes in the darkness. He's come into a warren of hallways, offices. He waits until his eyes adjust, then steps carefully around a stack of chairs, thick with dust. He almost trips over an ancient fax machine on the floor.

* * *

_"Promise me, Stiles."_

_Stiles looks up at his father and swallows past the lump in his throat. "Sure," he says. "I promise." He looks back down at the kitchen table, locks his eyes to a deep scratch in the varnish that's been there as long as he can remember. "It's not like I can go after her by myself, after all. Scott won't help me. Peter won't help me." He looks up. "You won't help me."_

_"Stiles..." The sheriff pulls out a chair and sits down opposite. "I know you cared about him—"_

_Stiles snorts. "Cared."_

_"Care," the sheriff says. "You_ _**care** _ _about him. I know. But I need you to be safe, do you understand that? And the slim chance he might be still alive isn't worth it."_

_"Of course not," Stiles whispers._

* * *

There's a pale, flickering glow up ahead. As Stiles creeps forward, a single fluorescent bulb comes into view on the low ceiling. It ticks as it flickers.

Stiles is on a mezzanine that runs around the edge of the room, a set of dusty stairs leading down to the floor below. He chokes, like something hits him hard in the chest, when he sees what lies in the center of the room.

There's so much blood.

Derek lies in a pool of it, so thick it looks black until the overhead light flickers and gives it a crimson shine.

Stiles takes one instinctive step, and then stops.

* * *

_"If we wait, it might be too late."_

_Chris Argent leans over his desk, palms flat on the surface. "I've contacted every hunter I know that goes by the code. Deaton is reaching out to other packs. When they come—"_

_"Derek will be dead," Stiles spits. "She's getting bored, can't you see that? She finds him, kicks his ass, leaves him almost dead. Then as soon as he's on his feet, she does it again. But this is different. This is the main course, the thing she's been looking forward to. She's going to take him apart." There's something lodged in his throat, something sharp that he can't swallow back. He blinks away the sting in his eyes, ignores the tear that rolls down his cheek and soaks into his shirt. "And I'm the only one who gives a shit."_

_Chris looks down, stares hard at the backs of his hands. Then he pushes back and opens a drawer. He pulls out something that looks like a long, narrow knife with a dark wood handle in a battered leather sheath, lays it down on the surface of his desk._

* * *

Derek's not moving at all. He's naked to the waist, barefoot, and his jeans are torn and soaked with blood. Face down on the floor, all Stiles can see of him is his back, slashed open with evenly spaced cuts. The wounds look old, and don't appear to be healing.

He looks dead already.

Stiles picks his way carefully down the stairs, freezing with every creak of the boards. There's a great darkness at one end of the warehouse, the only part he can't see, and if she's going to come from anywhere, it'll be there. So far she hasn't.

If Derek is dead, Stiles hopes Kate hasn't left yet.

He makes it across the room with no sound or movement from the dark end of the warehouse, but neither is there a single sign of life from the floor.

He drops into a crouch, lays a hand on the back of Derek's neck. He breathes a sigh of relief at the warmth of his skin, slides two fingers around and finds a pulse, grins at the rattling breath he feels. "Thank god," he whispers. "Derek."

Derek lets out a choked moan, and his eyelids slowly open. "Stiles," he rasps. His arm moves, fingernails scratching at the slick boards as he tries to reach out. "Scott... Chris..."

Stiles shakes his head. "It's just me. Come on, we're getting out of here."

Derek jerks, eyes going wide, mouth opening in shock. He gets a hand beneath him, tries to push himself up but fails. "No. Get out, get out now, she's still—"

Laughter echoes. Stiles looks up, toward the darkness at the other end of the warehouse.

"Aww, this is so sweet, Derek. Your little boytoy came to rescue you." Kate walks slowly into view, heeled boots ringing out on the wooden floor. "He's not very smart, is he?"

"Stiles," Derek begs. "Go. _Please_."

Stiles gets to his feet, palming a jar from his pocket. "You're safe," he whispers, and then he flicks the cork out with his fingernail and locks his eyes to Kate's smirk. "I'm not going anywhere."

He flings the contents of the jar straight up, and black powder falls back down to form a perfect circle around Derek and himself. He drops the jar to the floor, watches as Kate's eyes follow it, as satisfaction blends to anger on her face, then he smoothly pulls his father's gun from the back of his jeans and flicks the safety off.

Kate's eyes follow that, too, stare down the barrel at Stiles for a split second before she turns, hair flying, to run.

Stiles sees it in slow motion, each of her steps like she's moving in water. He aims, fires, the crack of the bullet as it leaves the gun reverberating off the walls, the force making his whole body jerk. She goes down, he aims and fires at the back of her other knee, and she hits the floor.

Her screams fade into a howl as she shifts, but it doesn't stick. Pain, he thinks, and smiles as he places the gun carefully on the floor.

Then he calmly steps over the line of mountain ash.

"Stiles," Derek says. "Don't."

"It's okay," Stiles says, eyes still on Kate as he moves toward her. Her struggles cease and she goes limp.

"You don't have to do this." Derek whispers.

"Yeah, I do." Stiles pulls the stiletto from his pocket, slides it out of the sheath.

"What did you do to me?" Kate spits, neck muscles straining as she tries to push herself up off the floor. "I'm gonna kill you, you little bastard."

"Kanima venom on the bullets," Stiles says. "You'll heal, but you're not going anywhere." He reaches down, tugs at her shoulder, rolls her over onto her back, then steps over and puts a knee on the floor either side of her waist. He waves the stiletto in front of her face, sees her eyes widen. "Yeah, you know this, don't you."

* * *

_"It belonged to my wife," Chris says as he lifts it, slides the ancient leather sheath off to expose a long, narrow blade. Stiles wonders what it means, that this might help save the life of the werewolf whose bite forced her to kill herself._

_He watches closely as Chris pries off a cap at the end of the handle, shows him the mechanism inside. He can't stop the grin that spreads across his face as hope starts to come back. "Help me," he says._

_Chris sighs and shakes his head. "She's my sister. I can't."_

_"Why aren't you giving this to Scott?"_

_Chris slides the stiletto back into its sheath and pushes it across the desk toward Stiles. "Scott isn't a killer."_

_"But I am?"_

_"You could be."_

* * *

It takes him a moment to line it up, to be sure the blade will reach her heart. Behind him, Derek begs him to stop, beneath him, Kate has gone from threats to feral growls. Stiles blocks it all out, finds the space between her ribs, then he pushes down.

The needle-sharp point slides in slow, breaking through her skin, cutting through muscle. Stiles' knees come off the floor as he feels resistance, then it sinks in the final inch.

He feels the click as the mechanism fires, injecting wolfsbane directly into Kate's heart.

She goes rigid beneath him. Stiles pulls the stiletto free, and it falls from his fingers, drops to the floor with a clatter. Blood wells up from the tiny wound, red at first, then flows dark like an oil slick. Kate chokes on her last breaths, black spittle staining her lips.

She goes still. Stiles watches in fascination as her pupils dilate to eclipse the iris and take on a milky sheen.

"Stiles."

He turns, rising to his feet, stepping away from the body. "Derek?"

He's pushed himself upright, and now Stiles can see the mess that is his chest and stomach. There are patches of blistered skin and raw, open wounds, electrical burns, but Stiles' anger simmers under the surface now, it doesn't call for action.

He crosses the room, drags his foot through the line of mountain ash to break the circle, crouches and lifts his hand to slide his fingers through Derek's hair, to brush his thumb over Derek's temple. "It's over," he says.

Derek wraps his hand around Stiles' wrist. His fingers are covered in blood, his fingernails caked with dirt. "I'm sorry."

Stiles frowns. "No. She would have killed you this time. I wasn't going to let that happen." He holds Derek beneath the arms, helps him rise to his feet. "Come on."

"I didn't want you to have to kill for me." Derek's voice is rough and broken.

"I'd fucking die for you," Stiles says.

* * *

Derek passes out in the passenger seat of the Jeep.

Stiles goes back into the warehouse.

It's almost too easy to strip a couple of wires and twist them together before turning on the mains. Stiles stands at the top of the stairs and watches as the fire starts to burn, as it licks at the edges of Kate's hair and clothes. He stays as long as he can, just to be sure.

Derek opens his eyes when Stiles starts the Jeep. "She's not coming back," he says as he throws it into gear and pulls out of the alley. "Not this time."

 

**Author's Note:**

> If you enjoyed reading, please hit the [Kudos ♥] button.
> 
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